#!/usr/bin/env python

def sqroot(n):
    x = 1
    for i in range(100):
        x = (x + n/x)/2
    return x

x1, y1, x2, y2 = input().split()
x1 = float(x1)
x2 = float(x2)
y1 = float(y1)
y2 = float(y2)

distance = sqroot((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1))

print("%.8f" % distance) def sqroot(n):
    x = 1
    for i in range(100):
        x = (x + n/x)/2
    return x sqroot x = 1 x 1 for i in range(100):
        x = (x + n/x)/2
     i range(100) range 100 x = (x + n/x)/2 x (x + n/x)/2 x + n/x x n/x n x 2 return x x n n x1, y1, x2, y2 = input().split() x1 input().split() ().split () input split y1 x2 y2 x1 = float(x1) x1 float(x1) float x1 x2 = float(x2) x2 float(x2) float x2 y1 = float(y1) y1 float(y1) float y1 y2 = float(y2) y2 float(y2) float y2 distance = sqroot((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1)) distance sqroot((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1)) sqroot (x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1) (x2 - x1)*(x2 - x1) x2 - x1 x2 x1 x2 - x1 x2 x1 (y2 - y1)*(y2 - y1) y2 - y1 y2 y1 y2 - y1 y2 y1 print("%.8f" % distance) print "%.8f" % distance "%.8f" distance y2 = input().split() input().split() y2 x1 = float(x1) float(x1) x1 def sqroot(n):
    x = 1
    for i in range(100):
        x = (x + n/x)/2
    return x def sqroot(n):
    x = 1
    for i in range(100):
        x = (x + n/x)/2
    return x sqroot y1, x2, y2 = input().split() input().split() y1 y1 = float(y1) float(y1) y1 x2, y2 = input().split() input().split() x2 y2 = float(y2) float(y2) y2 distance = sqroot((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1)) sqroot((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1)) distance x1, y1, x2, y2 = input().split() input().split() x1 x2 = float(x2) float(x2) x2
#!/usr/bin/env python

def sqroot(n):
    x = 1
    for i in range(100):
        x = (x + n/x)/2
    return x

x1, y1, x2, y2 = input().split()
x1 = float(x1)
x2 = float(x2)
y1 = float(y1)
y2 = float(y2)

distance = sqroot((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1))

print("%.8f" % distance)